Typically, conventional refrigerant and air-conditioning units include four major components, namely, compressor, condenser, throttling device and evaporator.
A prior art condenser 10 generally adopts the structure as illustrated in FIG. 1, which has a refrigerant entrance 11, a refrigerant exit 15, a baffle plate 12 and a condensing tube bundle 13 being disposed or positioned inside the condenser 10, a subcooler 14 generally being further disposed or positioned at a bottom of the condenser 10.
A prior art falling film evaporator 20 with the characteristics such as higher heat transfer efficiency and lower refrigerant charge has been more and more frequently applied to the vapor compression systems in refrigeration, air conditioning and chilled liquid systems. The prior art falling film evaporator 20 generally adopts the structure as illustrated in FIG. 2, including an evaporator exit pipe 21, a feeding pipe 22, a refrigerant distributor 23 and an evaporating tube bundle 24. The refrigerant distributor 23 in FIG. 2 is a key component of the falling film evaporator 20, and in order to achieve uniform distribution of the refrigerant to the evaporating tube bundle 24, it is necessary that sufficient pressure difference exists between an interior and an exterior of the refrigerant distributor 23. In a system with middle and high-pressure refrigerant (e.g. R134a, etc.), the pressure difference between the interior and the exterior of the refrigerant distributor 23 generally reaches 150-300 kPa.
The low-pressure refrigerant R1233zd(E) has received increased attention in the HVAC&R industry due to its advantages such as environmental friendliness and high efficiency, etc. Under a typical working condition (evaporation temperature 5° C., condensation temperature 36.7° C.), in a comparison between R1233zd(E) and R134a in terms of evaporation pressure and condensation pressure, the difference between the evaporation pressure and the condensation pressure of R1233zd(E) is only 23.1% of that of R134a. With respect to low-pressure refrigerants like R1233zd(E), the refrigerant distributor 23 in the conventional or prior art falling film evaporator 20 may not be able to satisfy operating load requirements.
Accordingly, there is a need for a condensation and falling film evaporation hybrid heat exchanger that can be used with low-pressure refrigerant, thus efficiently solving the problem of refrigerant distribution with the falling film evaporator using low-pressure refrigerant.